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Return-Path: Martin.Ward@durham.ac.uk
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Thu, 20 Jan 94 11:46:29 GMT
From: Martin.Ward@durham.ac.uk (Martin Ward)
Date: Thu, 20 Jan 94 11:46:27 GMT
Message-Id: <AA00871.9401201146.ws-csm3@uk.ac.durham>
To: des0mpw@easby.durham.ac.uk, lwall@scalpel.netlabs.com
Subject: Re: My last message
>: After saying I was stumped, I managed to track down the problem!
>: The problem was caused by a line much higher up:
>:
>: $seqpat = "$bs[s]\000e\000q\000\{\000"; # } hack
>:
>: Changing this by adding {} gives:
>:
>: $seqpat = "${bs}[s]\000e\000q\000\{\000"; # } hack
>:
>: which worked! No idea why :-)
>
>It apparently intuited $bs[s] to be an array reference.
Aha! I think the interpretation is:
"$bs[ s] .....
^^^^^ ^^
array ref Therefore this is an expression, so "s]" is the start of
a pattern match/replace, so it scans for ...]....]
I found the line by repeatedly chopping away everything after (and including)
the line where perl _thought_ the error started. This gradually worked back
through a nasty cascade of errors!
>: No speed improvement this time (the improvement in user time was swamped
>: by an increase in system time. This may be because it uses 5048k of
>: data/stack space, compared with 985k for perl4).
>
>That doesn't sound good. I hope it's a bug. Does it grow continuously?
>Hopefully it's just a memory leak.
For perl4 the memory size (shown by top) grows by about 100-150k per 2 seconds,
for perl5 it grows by about 1 - 1.5 Meg per 2 seconds. I don't use the script
very often (and I have over 100 Meg of swap space) so its not a big problem.
Still, with a 124k input file, the size for perl5 went up to 40 Meg!
I have tracked down a memory leak, which is basically one line from the
texqed script. Store this script in "tmp" and run "perl tmp /vmunix"
(or some other large random file). Monitor the process using "top" in
another window.
Perl4 is OK but perl5 leaks like a leaky cistern.
#!/usr/local/bin/perl
# print a "." every $interval lines:
$interval = 10;
open (PAIRS, "$ARGV[0]");
open (OUT, "> /dev/null");
$bs = "\\\\" . "\000";
for (;;) {
$line++;
if (($line % $interval) == 0) {
print STDERR ".";
}
read(PAIRS, $_, 20);
last if ($_ eq "");
s/$bs([_^\\])\000/\\\377$1\377/g;
print OUT ;
}
print STDERR "\n";
I hope you find this useful!
NB Changing the "s/.../.../g" to an "m/.../" (with the same pattern)
makes the leak go away even on input files where the pattern NEVER matches!!
Martin.
JANET: Martin.Ward@uk.ac.durham Internet (eg US): Martin.Ward@durham.ac.uk
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